Image forming apparatus having motor, and motor control apparatus for controlling motor

Abstract

An image forming apparatus includes: a motor; a transfer mechanism configured to transfer driving force of the motor to a load; and a control unit configured to control the motor to rotate a rotor of the motor in a first direction to rotate the load. The transfer mechanism has backlash, and the control unit is further configured to, when control to rotate the rotor in the first direction fails, determine whether or not control to rotate the rotor in the first direction failed due to the motor being faulty, by executing control to rotate the rotor a predetermined amount in a second direction opposite to the first direction.

What is claimed is: 
     
       1. An image forming apparatus comprising:
 a motor; 
 a transfer mechanism configured to transfer driving force of the motor to a load; and 
 a control unit configured to control the motor to rotate a rotor of the motor in a first direction to rotate the load, 
 wherein the transfer mechanism has backlash, and 
 the control unit is further configured to, when control to rotate the rotor in the first direction fails, determine whether or not control to rotate the rotor in the first direction failed due to the motor being faulty, by executing control to rotate the rotor a predetermined amount in a second direction opposite to the first direction. 
 
     
     
       2. The image forming apparatus according to  claim 1 ,
 wherein the predetermined amount is less than or equal to a backlash amount of the backlash. 
 
     
     
       3. The image forming apparatus according to  claim 2 ,
 wherein the control unit is further configured to determine that the motor is faulty when a phase difference between a rotational phase of the rotor before being rotated in the second direction and a rotational phase of the rotor after being rotated in the second direction is less than a predetermined value. 
 
     
     
       4. The image forming apparatus according to  claim 3 ,
 wherein the predetermined amount is an amount to make the phase difference greater than or equal to the predetermined value. 
 
     
     
       5. The image forming apparatus according to  claim 2 ,
 wherein the control unit is further configured to determine that the motor is faulty when a phase difference between a rotational phase of the rotor after being rotated in the second direction and a rotational phase of the rotor in the case of assuming the rotor has been rotated by the predetermined amount in the second direction is greater than or equal to a predetermined value. 
 
     
     
       6. The image forming apparatus according to  claim 5 ,
 wherein the predetermined amount is an amount greater than or equal to the predetermined value. 
 
     
     
       7. The image forming apparatus according to  claim 1 ,
 wherein the control unit is further configured to determine that the load is faulty when, according to a result of executing control to rotate the rotor by the predetermined amount in the second direction, the motor is not determined to be faulty. 
 
     
     
       8. The image forming apparatus according to  claim 1 ,
 wherein the control unit determines that control to rotate the rotor in the first direction has failed when, after executing control to rotate the rotor in the first direction at a rotation speed greater than a predetermined speed and detecting a rotation speed of the rotor, the detected rotation speed of the rotor is less than the predetermined speed. 
 
     
     
       9. The image forming apparatus according to  claim 1 ,
 wherein the load is photosensitive member. 
 
     
     
       10. The image forming apparatus according to  claim 1 ,
 wherein the transfer mechanism includes a coupling; and 
 the backlash is provided in the coupling. 
 
     
     
       11. An image forming apparatus comprising:
 a motor; 
 a transfer mechanism configured to transfer driving force of the motor to a first load when a rotor of the motor is rotating in a first direction and transfer driving force of the motor to a second load different from the first load when the rotor is rotating in a second direction opposite to the first direction; and 
 a control unit configured to control the motor, 
 wherein the control unit is further configured to, when control to rotate the rotor in the first direction fails, determine whether or not control to rotate the rotor in the first direction failed due to the motor being faulty by executing control to rotate the rotor in the second direction and determining whether or not control to rotate the rotor in the second direction fails. 
 
     
     
       12. The image forming apparatus according to  claim 11 ,
 wherein the control unit is further configured to determine that the motor is faulty when control to rotate the rotor in the second direction fails. 
 
     
     
       13. The image forming apparatus according to  claim 12 ,
 wherein the control unit is further configured to determine that the first load is faulty when control to rotate the rotor in the second direction does not fail. 
 
     
     
       14. The image forming apparatus according to  claim 11 ,
 wherein the control unit is further configured to determine that control to rotate the rotor in the first direction has failed when, after executing control to rotate the rotor in the first direction at a rotation speed greater than a first predetermined speed and detecting a rotation speed of the rotor, the detected rotation speed of the rotor is less than the first predetermined speed. 
 
     
     
       15. The image forming apparatus according to  claim 11 ,
 wherein the control unit is further configured to determine that control to rotate the rotor in the second direction has failed when, after executing control to rotate the rotor in the second direction at a rotation speed greater than a second predetermined speed and detecting a rotation speed of the rotor, the detected rotation speed of the rotor is less than the second predetermined speed. 
 
     
     
       16. The image forming apparatus according to  claim 11 ,
 wherein the first load is a pressure roller of a fixing unit that includes a heating roller and the pressure roller; and 
 the second load is an abutment/separation portion configured to set the fixing unit to an abutment state in which the pressure roller is abutted against the heating roller or a separated state in which the pressure roller is separated from the heating roller. 
 
     
     
       17. The image forming apparatus according to  claim 16 , further comprising:
 a detection portion configured to detect whether the fixing unit is in the abutment state or the separated state, 
 wherein the control unit is further configured to determine that the first load and the second load are faulty when, in a case in which control to rotate the rotor in the second direction does not fail, the state of the fixing unit is unchanged. 
 
     
     
       18. A motor control apparatus for controlling a motor configured to transfer driving force to a load via a transfer mechanism having backlash, the motor control apparatus being configured to:
 rotate a rotor of the motor in a first direction to rotate the load, 
 determine whether control to rotate the rotor in the first direction has failed, and 
 in response to control to rotate the rotor in the first direction being determined to have failed, determine whether or not control to rotate the rotor in the first direction failed due to the motor being faulty by executing control to rotate the rotor by a predetermined amount in a second direction opposite to the first direction. 
 
     
     
       19. A motor control apparatus for controlling a motor configured to transfer driving force to a first load and a second load via a transfer mechanism,
 wherein the transfer mechanism is configured to transfer the driving force to the first load when a rotor of the motor rotates in a first direction and transfer the driving force to the second load when the rotor rotates in a second direction opposite to the first direction, 
 the motor control apparatus being configured to: 
 rotate the rotor in the first direction to rotate the first load, 
 determine whether control to rotate the rotor in the first direction failed, in response to control to rotate the rotor in the first direction being determined to have failed, execute control to rotate the rotor in the second direction, and 
 determine whether or not control to rotate the rotor in the first direction failed due to the motor being faulty by determining whether control to rotate the rotor in the second direction failed.